1. Field of the Invention
The present invention relates to a forage harvester and more particularly to a chopping and propelling apparatus adapted to be mounted in such harvester. The purpose of a machine of the above type is to chop forage greens, more particularly corn. Now, the only part of corn which is truly of nutritive value for animals are the grains and these have to be cut open in order truly to be of worth as otherwise they would not be absorbed by the stomach of the animal.
2. Description of the Prior Art
Forage harvesters of the prior art are characteristically inefficient in both construction and manner of operation. Thus it is usual to use only one rotor intended for carrying the dual operation of chopping and propelling. This approach is particularly inefficient in view of the fact that the chopper blades are not designed to provide a propelling function and thus little centrifugal action is achieved thereby. On the other hand, if the design is altered so as to improve the propelling effect, this is inevitably done at the lose of efficiency in the chopping operation which, as mentioned previously, is important in this type of apparatus to provide adequate breaking up of the corn grains. A single rotor forage harvester of this type is disclosed in the Danish Pat. No. 93,543 of May 28, 1962.
Attempts have been made to avoid the above-mentioned difficulty by providing, along with the chopping rotor, a cooperating auxiliary of boosting impeller intended specifically to propel the chopped forage. U.S. Pat. No. 3,805,660 of Apr. 23, 1974 is typical of this type of equipment intended to promote a greater degree of efficiency. However, in the latter patent, the boosting impeller is arranged for rotation about an axis which is perpendicular to the axis of rotation of the chopper rotor. The forage which is cut by the chopper rotor must of necessity undergo a 90.degree. change in flow direction when it is subjected to the propelling action of the boosting impeller. A harvester of this type is therefore inefficient due to the fact that the flow of forage which is chopped and propelled does not travel in a smoothly continuous flow.